Psamtik III (also spelled Psammetichus or Psammeticus) is the last Pharaoh of the Twenty-sixth Dynasty of Egypt from 526 BCE to 525 BCE.

Most of what is known about his reign and life was documented by the Greek historian Herodotus in the 5th century.

Herodotus states that Psamtik had ruled Egypt for only six months before he was confronted by a Persian invasion of his country led by King Cambyses II of Persia.

Psammetichus is subsequently defeated at Pelusium, and flees to Memphis where he is captured.

The deposed pharaoh is carried off to Susa in chains, and later executed.